EP0029520B1 - Method for the separation of gases developed by a fusion electrolysis, and fusion electrolysis apparatus - Google Patents

Method for the separation of gases developed by a fusion electrolysis, and fusion electrolysis apparatus Download PDF

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Publication number
EP0029520B1
EP0029520B1 EP80106653A EP80106653A EP0029520B1 EP 0029520 B1 EP0029520 B1 EP 0029520B1 EP 80106653 A EP80106653 A EP 80106653A EP 80106653 A EP80106653 A EP 80106653A EP 0029520 B1 EP0029520 B1 EP 0029520B1
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EP
European Patent Office
Prior art keywords
diaphragm
cathode
electrolysis
fusion electrolysis
separator
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EP80106653A
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German (de)
French (fr)
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EP0029520A1 (en
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Jiri Dr. Divisek
Jürgen Mergel
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Forschungszentrum Juelich GmbH
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Forschungszentrum Juelich GmbH
Kernforschungsanlage Juelich GmbH
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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B1/00—Electrolytic production of inorganic compounds or non-metals
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B1/00—Electrolytic production of inorganic compounds or non-metals
    • C25B1/01—Products
    • C25B1/02—Hydrogen or oxygen
    • C25B1/04—Hydrogen or oxygen by electrolysis of water
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B13/00—Diaphragms; Spacing elements
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B9/00—Cells or assemblies of cells; Constructional parts of cells; Assemblies of constructional parts, e.g. electrode-diaphragm assemblies; Process-related cell features
    • C25B9/70—Assemblies comprising two or more cells
    • C25B9/73—Assemblies comprising two or more cells of the filter-press type
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
    • C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
    • C25C7/00—Constructional parts, or assemblies thereof, of cells; Servicing or operating of cells
    • C25C7/04—Diaphragms; Spacing elements
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/36—Hydrogen production from non-carbon containing sources, e.g. by water electrolysis

Definitions

  • the invention relates to a method for separating the gases electrolytically developed on the cathode or on the anode during melt flow electrolysis by means of a fine-pored, electrically conductive separator, and to a melt flow electrolysis device suitable for this.
  • a particular field of application of the invention is the melt flow electrolysis of water vapor in an alkali hydroxide melt for the production of hydrogen from water.
  • the inventive method of the type mentioned is characterized in that cathodic polarization protection of the separator is provided.
  • DE-B2-2 637633 already discloses a method for corrosion protection of metallic objects in general, such as Containers, known, in which the passive state of the pulsating anodically protected object is to be improved by briefly short-circuiting the cathode with the aid of a potential regulator (during the breaks).
  • this corrosion protection process is difficult to incorporate into alkaline water electrolysis.
  • a porous sintered metal diaphragm between the anode and cathode is used as the separator, which is electrically connected to the cathode via a variable resistor, which is set or regulated in such a way that a maximum discharge current of less than about 1% of the total load on the electrolysis at the diaphragm occurs.
  • a suitable diaphragm for the alkaline melt flow electrolysis of water is, in particular, a porous nickel membrane, such as is obtained, for example, by applying a binder-containing metal powder composition to a metal network with subsequent firing and sintering of the powder in hydrogen.
  • the porosity of a nickel diaphragm produced in this way is preferably at least about 70%, with about 80% of the pores being smaller than 10 ⁇ m.
  • a porous diaphragm was produced in the following way: A nickel powder mass pasted with a rubber solution in toluene as a binder in a total amount of 50 mg / cm 2 was placed on both sides of a nickel mesh (mesh size 0.25 mm, wire thickness 0.35 mm) Mesh carrier applied or coated as a layer of nickel powder.
  • the INCO nickel powder type 255 used had a particle size of 2.3 to 3 ⁇ m. After sintering under hydrogen at 800 ° C. for 15 minutes, a 0.5 mm thick metal sintered diaphragm with 80% porosity was obtained. 80% of the pores were smaller than 10 ⁇ m.
  • the specific surface resistance measured in 7n KOH at 20 ° C was 0.10 Qcm2. This excellent value is of course even lower at the working temperature (approx. 350 ° C).
  • the purity of the gases H Z / O 2 which could initially only be tested at 75 ° C and 1 A / cm 2 , was 0.20%.
  • this diaphragm dissolves in the hydroxide melt in just a few hours.
  • the diaphragm is loaded with a protective current of only 1 mA / cm 2 at an electrolysis current density of 500 mA / cm 2 , adequate corrosion protection is obtained, such as through a long-term test over more than 500 hours in the NaOH melt at 360 ° C was proven.
  • the diaphragm was still fully functional at the end of the experiment. The measured power loss, which - if it were considerable - could lead to a dangerous formation of oxyhydrogen gas, is completely negligible.
  • the attached sketch shows a circuit for carrying out the above method: the electrolysis cell 1, which is supplied with voltage from a direct current source, is divided into an anode and a cathode space by a fine-pored, electrically conductive diaphragm 2.
  • This diaphragm 2 is connected to the cathode via a connecting line 3, in which a variable resistor 4 and optionally an ammeter 5 are provided.
  • the dimensioning of the resistance depends on the cell dimensions and the conductivity of the electrolyte, whereby special values could easily be estimated on the basis of Ohm's law. Usual values will be in the range of 500 to 5000 Q.

Description

Die Erfindung bezieht sich auf ein Verfahren zur Trennung der an der Kathode beziehungsweise an der Anode bei einer Schmelzflusselektrolyse elektrolytisch entwickelten Gase durch einen feinporigen, elektrisch leitenden Separator sowie auf eine dafür geeignete Schmelzflusselektrolysevorrichtung.The invention relates to a method for separating the gases electrolytically developed on the cathode or on the anode during melt flow electrolysis by means of a fine-pored, electrically conductive separator, and to a melt flow electrolysis device suitable for this.

Ein besonderes Anwendungsgebiet der Erfindung ist die Schmelzflusselektrolyse von Wasserdampf in einer Alkalihydroxidschmelze zur Herstellung von Wasserstoff aus Wasser.A particular field of application of the invention is the melt flow electrolysis of water vapor in an alkali hydroxide melt for the production of hydrogen from water.

Für die zukünftige Wasserstofftechnologie ist die wirtschaftliche Wasserstoffproduktion eine der wesentlichen Voraussetzungen. Es zeigt sich dabei, dass die Elektrolyse von in geschmolzenen Hydroxyden gelöstem Wasserdampf eine besonders vorteilhafte Art der Wasserstoffherstellung ist: Durch die dabei zwangsläufig gegebene erhöhte Arbeitstemperatur wird der Elektrolysevorgang sowohl energetisch als auch kinetisch weitgehend begünstigt.Economic hydrogen production is one of the essential prerequisites for future hydrogen technology. It turns out that the electrolysis of water vapor dissolved in molten hydroxides is a particularly advantageous way of producing hydrogen: the inevitably increased working temperature means that the electrolysis process is largely favored both energetically and kinetically.

Die einerseits günstige Anwendung erhöhter Temperaturen beschleunigt allerdings anderseits unerwünschte Vorgänge, die bei niedrigeren Temperaturen gehemmt sind, wie z. B. die Korrosion. Um dem Korrosionsangriff wirksam zu begegnen, wählt man üblicherweise solche Materialien für die Elektrolysezelle und die Elektroden, die in genügendem Masse korrosionsbeständig sind. Diese gängige Art, einem Korrosionsangriff zu begegnen, zwingt jedoch häufig dazu, sehr teure oder seltene Materialien zu verwenden oder auch solche Stoffe, deren Anwendung mit negativen Begleiterscheinungen verbunden ist, wie nachfolgend näher erläutert wird:

  • Ein besonderes Problem bildet die Auswahl eines geeigneten Diaphragmamaterials für geschmolzene Hydroxide, deren hoher Korrosivität nur wenige bekannte Materialien widerstehen können, so dass die Zahl der zur Verfügung stehenden Materialien stark begrenzt ist. Kunststoffe, zum Beispiel Teflon, sind wegen ihrer zu geringen Temperaturbeständigkeit nicht geeignet. Man kennt für diesen Zweck nur einige Metalloxide oder Oxidgemische. Folgt man den Literaturangaben (H. Lux, E. Renauer, E. Betz: Z. anorg. allg. Chemie, 310, [1961], 305), so kommen im wesentlichen nur Al2O3, HfO2, ZrO2 oder ThO2 in Betracht.
On the one hand, the favorable use of elevated temperatures, on the other hand, accelerates undesired processes that are inhibited at lower temperatures, such as, for. B. the corrosion. In order to counteract the corrosion attack effectively, such materials for the electrolytic cell and the electrodes are usually chosen that are sufficiently resistant to corrosion. However, this common way of counteracting a corrosion attack often forces the use of very expensive or rare materials or also substances whose use is associated with negative side effects, as will be explained in more detail below:
  • A particular problem is the selection of a suitable diaphragm material for molten hydroxides, the high corrosiveness of which only a few known materials can withstand, so that the number of available materials is very limited. Plastics, for example Teflon, are not suitable due to their low temperature resistance. Only a few metal oxides or oxide mixtures are known for this purpose. If one follows the references (H. Lux, E. Renauer, E. Betz: Z. anorg. Allg. Chemie, 310, [1961], 305), essentially only Al 2 O 3 , HfO 2 , ZrO 2 or ThO 2 into consideration.

Die Beständigkeit des billigsten dieser Oxide, nämlich des Al2O3, ist allerdings in der Hydroxidschmelze so eingeschränkt, dass jegliche poröse Struktur ausgeschlossen werden muss und nur irgendeine kompakte Form geeignet ist. Aus diesem Grunde wurden von der Anmelderin bereits (nichtporöse) Trennwände aus β-Al2O3, das ein Feststoffelektrolyt ist, vorgeschlagen. Das β-Al2O3 ist vorläufig jedoch noch nicht allgemein zugänglich und nur bei einer beschränkten Anzahl von Forschungsstätten verfügbar. Ferner ist die Entwicklung des Preises nur schwer abschätzbar und von vielen Faktoren abhängig, so dass es heikel . erscheint, eine grosstechnische Produktion darauf abzustellen.However, the resistance of the cheapest of these oxides, namely Al 2 O 3 , is so limited in the hydroxide melt that any porous structure must be excluded and only some compact form is suitable. For this reason, the applicant has already proposed (non-porous) partition walls made of β-Al 2 O 3 , which is a solid electrolyte. For the time being, however, the β-Al 2 O 3 is not yet generally accessible and only available at a limited number of research facilities. Furthermore, the development of the price is difficult to estimate and depends on many factors, making it tricky . appears to be based on a large-scale production.

Von den übrigen oben genannten Metalloxiden kommt eigentlich nur das poröse Zr02 in Frage. Dieses Oxid ist ebenfalls nicht billig und ausserdem sehr schwer in einer mechanisch genügend stabilen und gleichzeitig ausreichend porösen Form zu erhalten. Vermutlich lässt sich das Zusammentreffen beider Eigenschaften auch in Zukunft nur sehr beschränkt beim Zr02 erreichen.Of the other metal oxides mentioned above, only the porous Zr0 2 is actually suitable. This oxide is also not cheap and is also very difficult to obtain in a mechanically sufficiently stable and at the same time sufficiently porous form. Presumably, the combination of both properties can only be achieved to a very limited extent in the future with the Zr0 2 .

Auf der Suche nach einem billigen Diaphragma wurde auch schon versucht, Diaphragmen aus Metallnetzen zu verwenden (Winnacker-Küchler: Chemische Technologie, Band 6, S. 97). Diese haben jedoch zum einen nur eine schlechte Trennwirkung, die für die Wasserstoff/Sauerstoff-Separation völlig unzureichend ist, und zum anderen werden'sie von der Schmelze schon in einigen Tagen so stark angegriffen, dass sie sich zumindest teilweise auflösen.In the search for a cheap diaphragm, attempts have already been made to use diaphragms made of metal nets (Winnacker-Küchler: Chemische Technologie, Volume 6, p. 97). On the one hand, however, these have only a poor separation effect, which is completely inadequate for hydrogen / oxygen separation, and on the other hand, they are attacked by the melt so severely in a few days that they at least partially dissolve.

Dasselbe passiert auch mit einem Diaphragma, das aus gesintertem Metallpulver besteht. Ein solches Diaphragma besitzt zwar wegen seiner feinen Porosität hervorragende Separationseigenschaften, es ist jedoch gerade aus diesem Grund sehr korrosionsanfällig.The same thing happens with a diaphragm made of sintered metal powder. Such a diaphragm has excellent separation properties because of its fine porosity, but it is precisely for this reason that it is very susceptible to corrosion.

Nach einer älteren europäischen Patentanmeldung (EP-A-1-0 022 252) der Anmelderin wird ein solches, insbesondere mit einem Drahtnetz versehenes Sintermetalldiaphragma bei erhöhter Temperatur in sauerstoffhaltiger Atmosphäre so weit aufoxidiert, dass ein ausreichend isolierender, mechanisch angemessen stabiler Körper resultiert, der als Diaphragma für die alkalische Wasserelektrolyse brauchbar ist.According to an older European patent application (EP-A-1-0 022 252) by the applicant, such a sintered metal diaphragm, in particular provided with a wire mesh, is oxidized to such an extent at elevated temperature in an oxygen-containing atmosphere that a sufficiently insulating, mechanically appropriately stable body results is useful as a diaphragm for alkaline water electrolysis.

Es wurde nun gefunden, dass eine solche Oxidation vermieden werden kann, wenn man das Lösungspotential des Separators durch entsprechende Vorspannung herabsetzt. Das heisst, durch ausreichend kathodische Polung des metallischen Diaphragmas in der Elektrolysezelle wird der an sich bestehenden Lösungstendenz des metallischen Sinterkörpers ausreichend entgegengewirkt.It has now been found that such an oxidation can be avoided if the solution potential of the separator is reduced by appropriate biasing. This means that the cathode polarity of the metallic diaphragm in the electrolytic cell is sufficiently counteracted by the tendency of the metallic sintered body to dissolve.

Demgemäss ist das erfindungsgemässe Verfahren der eingangs genannten Art dadurch gekennzeichnet, dass ein kathodischer Polarisationsschutz des Separators vorgesehen wird.Accordingly, the inventive method of the type mentioned is characterized in that cathodic polarization protection of the separator is provided.

Aus der DE-B2-2 637633 ist zwar bereits ein Verfahren zum Korrosionsschutz von metallischen Gegenständen allgemein, wie z.B. Behältern, bekannt, bei dem der passive Zustand des pulsierend anodisch geschützten Gegenstandes durch kurzzeitigen Kurzschluss mit der Kathode mit Hilfe eines Potentialreglers (in den Pausen) verbessert werden soll. Dieses Korrosionsschutzverfahren lässt sich jedoch schwerlich in die alkalische Wasserelektrolyse einfügen.DE-B2-2 637633 already discloses a method for corrosion protection of metallic objects in general, such as Containers, known, in which the passive state of the pulsating anodically protected object is to be improved by briefly short-circuiting the cathode with the aid of a potential regulator (during the breaks). However, this corrosion protection process is difficult to incorporate into alkaline water electrolysis.

Vorzugsweise wird beim erfindungsgemässen Verfahren als Separator ein poröses Sintermetalldiaphragma zwischen Anode und Kathode verwendet, das elektrisch über einen Regelwiderstand mit der Kathode verbunden ist, der so eingestellt beziehungsweise geregelt wird, dass am Diaphragma ein maximaler Entladungsstrom von weniger als etwa 1% der Gesamtbelastung der Elektrolyse auftritt.Preferably, in the method according to the invention, a porous sintered metal diaphragm between the anode and cathode is used as the separator, which is electrically connected to the cathode via a variable resistor, which is set or regulated in such a way that a maximum discharge current of less than about 1% of the total load on the electrolysis at the diaphragm occurs.

Für die alkalische Schmelzflusselektrolyse von Wasser eignet sich als Diaphragma insbesondere eine poröse Nickelmembran, wie sie zum Beispiel durch Auftragen einer bindemittelhaltigen Metallpulvermasse auf ein Metallnetz mit nachfolgendem Brennen und Sintern des Pulvers in Wasserstoff erhalten wird. Die Porosität eines so hergestellten Nickel-Diaphragmas liegt vorzugsweise bei mindestens etwa 70%, wobei etwa 80% der Poren kleiner als 10 µm sind.A suitable diaphragm for the alkaline melt flow electrolysis of water is, in particular, a porous nickel membrane, such as is obtained, for example, by applying a binder-containing metal powder composition to a metal network with subsequent firing and sintering of the powder in hydrogen. The porosity of a nickel diaphragm produced in this way is preferably at least about 70%, with about 80% of the pores being smaller than 10 μm.

Eine zu stark negative Vorspannung des Diaphragmas sollte allerdings vermieden werden, damit sowohl mögliche Ladungsverluste als auch eine Wasserstoffentwicklung im Anodenraum mit der Gefahr der Knallgasexplosion nicht ins Gewicht fallen.An excessively negative bias of the diaphragm should be avoided, however, so that possible charge losses as well as hydrogen development in the anode compartment with the risk of detonating gas explosion are neglected.

Nachfolgend wird die Erfindung anhand eines speziellen Ausführungsbeispiels beschrieben.The invention is described below on the basis of a special exemplary embodiment.

Beispiel Ein poröses Diaphragma wurde in folgender Weise hergestellt: Auf ein Nickelnetz (Maschenweite 0,25 mm, Drahtstärke 0,35 mm) wurde eine mit einer Kautschuklösung in Toluol als Bindemittel angeteigte Nickelpulvermasse in einer Gesamtmenge von 50 mg/cm2 auf beide Seiten des Netzträgers als Nickelpulverschicht aufgetragen beziehungsweise gestrichen. Das verwendete INCO-Nickelpulver Typ 255 hatte eine Teilchengrösse von 2,3 bis 3 µm. Nach 15 Minuten Sintern unter Wasserstoff bei 800°C wurde ein 0,5 mm dickes Metallsinterdiaphragma mit 80%iger Porosität erhalten. 80% der Poren waren kleiner als 10 µm.EXAMPLE A porous diaphragm was produced in the following way: A nickel powder mass pasted with a rubber solution in toluene as a binder in a total amount of 50 mg / cm 2 was placed on both sides of a nickel mesh (mesh size 0.25 mm, wire thickness 0.35 mm) Mesh carrier applied or coated as a layer of nickel powder. The INCO nickel powder type 255 used had a particle size of 2.3 to 3 µm. After sintering under hydrogen at 800 ° C. for 15 minutes, a 0.5 mm thick metal sintered diaphragm with 80% porosity was obtained. 80% of the pores were smaller than 10 µm.

Der in 7n KOH bei 20°C gemessene spezifische Oberflächenwiderstand lag bei 0,10 Qcm2. Dieser ausgezeichnete Wert wird bei der Arbeitstemperatur (ca. 350°C) natürlich noch geringer. Die Reinheit der Gase HZ/O2, die zunächst nur bei 75 °C und 1 A/cm2 getestet werden konnte, lag bei 0,20%.The specific surface resistance measured in 7n KOH at 20 ° C was 0.10 Qcm2. This excellent value is of course even lower at the working temperature (approx. 350 ° C). The purity of the gases H Z / O 2 , which could initially only be tested at 75 ° C and 1 A / cm 2 , was 0.20%.

Kathodisch ungeschützt löst sich dieses Diaphragma in der Hydroxidschmelze schon in einigen Stunden auf. Belastet man das Diaphragma dagegen mit einem Schutzstrom von nur 1 mA/ cm2 bei einer Elektrolysestromdichte von 500 mA/ cm2, so erhält man einen ausreichenden Korrosionsschutz, wie durch einen Langzeitversuch über mehr als 500 Stunden in der NaOH-Schmelze bei 360 °C nachgewiesen wurde. Das Diaphragma war am Ende des Versuches noch voll funktionsfähig. Der gemessene Stromverlust, der-wenn er beachtlich wäre - gleichzeitig zu einer gefährlichen Bildung von Knallgas führen könnte, ist völlig vernachlässigbar.Unprotected cathodically, this diaphragm dissolves in the hydroxide melt in just a few hours. On the other hand, if the diaphragm is loaded with a protective current of only 1 mA / cm 2 at an electrolysis current density of 500 mA / cm 2 , adequate corrosion protection is obtained, such as through a long-term test over more than 500 hours in the NaOH melt at 360 ° C was proven. The diaphragm was still fully functional at the end of the experiment. The measured power loss, which - if it were considerable - could lead to a dangerous formation of oxyhydrogen gas, is completely negligible.

Die angefügte Skizze zeigt eine Schaltung für die Durchführung des vorstehenden Verfahrens: die von einer Gleichstromquelle mit Spannung versorgte Elektrolysezelle 1 wird durch ein feinporiges elektrisch leitendes Diaphragma 2 in einen Anoden- und einen Kathodenraum unterteilt.The attached sketch shows a circuit for carrying out the above method: the electrolysis cell 1, which is supplied with voltage from a direct current source, is divided into an anode and a cathode space by a fine-pored, electrically conductive diaphragm 2.

Dieses Diaphragma 2 steht mit der Kathode über eine Verbindungsleitung 3 in Verbindung, in der ein Regelwiderstand 4 und gegebenenfalls ein Amperemeter 5 vorgesehen sind. Die Dimensionierung des Widerstandes richtet sich nach den Zellabmessungen und der Leitfähigkeit des Elektrolyten, wobei spezielle Werte ohne weiteres unter Zugrundelegung des Ohmschen Gesetzes abgeschätzt werden könnten. Übliche Werte werden in der Gegend von 500 bis 5000 Q liegen.This diaphragm 2 is connected to the cathode via a connecting line 3, in which a variable resistor 4 and optionally an ammeter 5 are provided. The dimensioning of the resistance depends on the cell dimensions and the conductivity of the electrolyte, whereby special values could easily be estimated on the basis of Ohm's law. Usual values will be in the range of 500 to 5000 Q.

Claims (4)

1. Method for the separation of gases which are developed electrolytically at the cathode and at the anode respectively in a fusion electrolysis operation, through a fine-pored electrically conductive separator, characterised in that cathodic polarisation protection is provided for the separator.
2. Method according to claim 1, characterised in that a porous sintered metal diaphragm is provided as the fine-pored separator between anode and cathode, and is electrically connected to the cathode via a variable resistor which is so set or regulated that there occurs at the diaphragm a maximum discharge current of less than approximately 1% of the total electrolysis load.
3. Method according to claim 2, characterised in that a porous nickel membrane with a porosity of >70% is used as the diaphragm, approximately 80% of its pores being smaller than 10 µm.
4. Apparatus for fusion electrolysis with an electrolytic cell which is divided by a porous electrically conductive diaphragm into a cathode compartment and an anode compartment, and with a direct current source for applying the electrolysis voltage, characterised by a connecting line (3) with a variable resistor (4) and possibly an ammeter (5) between the cathode and the diaphragm (2).
EP80106653A 1979-11-24 1980-10-30 Method for the separation of gases developed by a fusion electrolysis, and fusion electrolysis apparatus Expired EP0029520B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE2947454A DE2947454C2 (en) 1979-11-24 1979-11-24 Process for the separation of the gases evolved in a fused flux electrolysis and a fused flux electrolysis device
DE2947454 1979-11-24

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EP0029520A1 EP0029520A1 (en) 1981-06-03
EP0029520B1 true EP0029520B1 (en) 1984-07-11

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DE (1) DE2947454C2 (en)

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JPH03115592A (en) * 1989-09-28 1991-05-16 Osaka Titanium Co Ltd Molten salt electrolytic cell
US6669837B1 (en) * 2002-12-17 2003-12-30 Sunbelt Chlor Alkali Partnership Alkali metal hydroxide evaporator system

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0022252A1 (en) * 1979-07-07 1981-01-14 Forschungszentrum Jülich Gmbh Diaphragm for the alkaline electrolysis of water, process for its manufacture and its use

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2637633C3 (en) * 1976-08-20 1980-02-07 Vladimir Grigorevitsch Mojsa Process for the corrosion protection of a metallic object in contact with an electrically conductive medium

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0022252A1 (en) * 1979-07-07 1981-01-14 Forschungszentrum Jülich Gmbh Diaphragm for the alkaline electrolysis of water, process for its manufacture and its use

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JPS5687685A (en) 1981-07-16
EP0029520A1 (en) 1981-06-03
CA1169018A (en) 1984-06-12
DE2947454C2 (en) 1982-05-06
DE2947454B1 (en) 1981-04-02

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